Ripple's XRP is now down more than 4% on Monday, paring its earlier gains, after Coinbase shut down yet another rumor that it was planning to support the cryptocurrency.

"We have made no decision to add additional assets to either GDAX or Coinbase," the company said in a tweet Monday afternoon.

XRP, the third-largest cryptocurrency by market cap, surged as much as 6% Monday morning after a planned CNBC segment Tuesday featuring both Coinbase President Asiff Hirji and Ripple CEO Brad Garlinghouse fueled rumors online that Coinbase might have been planning to announce support for XRP.